Decide which type of prop you wish to build. Props can include tables, chairs or almost any type of inanimate object. Measure the object you wish to create with measuring tape. You will need height, depth, width and circumference measurements as applicable. Draw a rough sketch of the object on a piece of paper and transfer the measurements to the sketch. Label each piece of the construction with a number designation.
Gather balsa foam, Styrofoam or cardboard in sheets, tube or block sizes that will accommodate all of the pieces you need to recreate for your prop. Label the pieces with the corresponding number designation.
Prepare the sculpting tools according to the manufacturer's recommendations, which might include heating the tools and removing any protective packaging. Use the scissors, sculpting tool, engraving tool and hot knife to carve the appropriate shaped pieces.
Assemble the pieces together one at a time using a Styrofoam adhesive or strong glue for the balsa foam. Spray the adhesive on one part, position it on the second part and allow the adhesive to dry completely before adding new pieces.
Paint the prop using spray paint. Allow the paint to dry completely.